CVE-2010-2249 in libpng
Summary
by MITRE
Memory leak in pngrutil.c in libpng before 1.2.44, and 1.4.x before 1.4.3, allows remote attackers to cause a denial of service (memory consumption and application crash) via a PNG image containing malformed Physical Scale (aka sCAL) chunks.
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Analysis
by VulDB Data Team • 09/19/2021
The vulnerability identified as CVE-2010-2249 represents a critical memory management flaw within the libpng library implementation that affects versions prior to 1.2.44 and 1.4.3. This issue specifically targets the pngrutil.c file which handles PNG image processing operations, creating a significant security risk for applications that rely on libpng for image handling. The vulnerability manifests when processing PNG images containing malformed Physical Scale chunks, which are used to specify the physical dimensions of the image in relation to the display device. These sCAL chunks contain two floating-point numbers representing the width and height of the image in physical units, but when improperly formatted or processed, they trigger unexpected behavior in the library's memory allocation routines.
The technical exploitation of this vulnerability occurs through the improper handling of sCAL chunk data during PNG image parsing operations. When libpng encounters malformed sCAL chunks, the library fails to properly manage memory allocation and deallocation processes, leading to a gradual accumulation of memory that is never released back to the system. This memory leak occurs because the library does not properly validate the structure and content of the sCAL chunks before attempting to process them, resulting in repeated memory allocations without corresponding deallocations. The flaw is particularly dangerous because it allows attackers to craft malicious PNG images that, when processed by vulnerable applications, will continuously consume system memory until the application crashes or the system becomes unresponsive.
From an operational perspective, this vulnerability creates a reliable denial of service condition that can be exploited remotely through any application that processes PNG images without proper input validation. Applications that are vulnerable include web browsers, image processing software, content management systems, and any software that uses libpng for image handling. The impact extends beyond simple resource exhaustion as the memory leak can cause applications to become unstable and crash, potentially leading to complete service disruption. The vulnerability is particularly concerning in web environments where users can upload or view PNG images from untrusted sources, making it a prime target for attackers seeking to disrupt online services or compromise system availability.
The security implications of CVE-2010-2249 align with CWE-401, which specifically addresses improper management of dynamic memory allocation, and can be categorized under the ATT&CK technique T1499.3 for resource exhaustion attacks. This vulnerability demonstrates the critical importance of input validation and proper memory management in security-sensitive libraries. The flaw represents a classic example of how seemingly benign image processing operations can become attack vectors when proper safeguards are not implemented. Organizations should prioritize immediate patching of affected libpng versions, implement input validation measures for PNG image processing, and consider deploying network-based intrusion detection systems to monitor for exploitation attempts. Additionally, application developers should ensure that their software properly handles error conditions and implements robust memory management practices to prevent similar vulnerabilities from occurring in their own codebases. The vulnerability underscores the necessity of thorough security testing for third-party libraries and the importance of maintaining up-to-date security patches across all system components.